The present invention relates generally to the field of imaging systems, specifically, medical imaging systems, and more specifically, ultrasonic imaging systems used in conjunction with electrosurgical biopsy instruments and methods.
In diagnosing and treating certain medical conditions, such as potentially cancerous tumors, it may be desirable to perform a biopsy, in which a specimen of the suspicious tissue is removed for pathological examination and analysis. In many instances, the suspicious tissue is located in a subcutaneous site, such as inside a human breast. To minimize surgical intrusion into patient""s body, it is often desirable to insert a small instrument into the body for extracting the biopsy specimen while imaging the procedure using x-ray, stereotactic x-ray, digital x-ray, fluoroscopy, ultrasonic imaging, MRI or any other suitable form of imaging technique.
Electrosurgical techniques have been used in a variety of circumstances, including certain types of biopsy procedures. In electrosurgery, high frequency electrical energy is applied through a primary electrode to patient tissue. The electrical energy flows through the tissue to a return electrode that is in contact with the patient""s tissue in monopolar electrosurgical systems. In bipolar electrosurgical systems, the electrical energy flows through the tissue from a primary electrode to a secondary electrode which is normally located on the same instrument as the primary electrode. Typically, the return electrode in monopolar systems is attached to the patient at a point remote from where the primary electrode contacts the tissue. The tissue adjacent the primary electrode can be ablated in order to form an opening in order to gain access to the tissue of interest. Thereafter, the tissue of interest can be ablated or cut with an electrosurgical electrode or any other suitable form of cutter in order to isolate a portion of the tissue of interest. Once the tissue of interest is isolated from surrounding tissue, it can be destroyed in situ, or can be removed for further analysis. An electrosurgical biopsy instrument is disclosed and claimed in U.S. patent application Ser. No. 09/159,467 for xe2x80x9cElectrosurgical Biopsy Device and Method,xe2x80x9d assigned to the assignee of the subject application, and which is hereby incorporated by reference in its entirety.
During such a procedure, it is critical to accurately access the precise location of the suspicious tissue within the patient""s body and to cut or isolate the suspicious tissue with precision so as to minimize trauma to surrounding healthy tissue. In order to accomplish this, it is generally necessary to accurately image the tissue of interest and surrounding tissue while the biopsy or surgical instrument is being positioned and activated. This gives the operator of the instrument visual feedback as to the relative position of the biopsy or surgical and suspicious tissue.
Ultrasonic imaging is frequently used to image the tissue of interest at the site of interest during a surgical or biopsy procedure. For example, during a breast biopsy procedure, the biopsy device is often imaged with ultrasonic imaging while the device is being inserted into the patient""s breast and activated to remove or isolate a sample of suspicious breast tissue. If the biopsy device is an electrosurgical device, this can be problematic because radiated electrical and electromagnetic noise from the electrosurgical probe creates noise and interference within the ultrasound image and video display of the image. The interference is typically so severe that the sonogram produced by the ultrasonic imaging system during the operation of an electrosurgical device is completely obscured. Thus, the operator is in effect blinded as to the relative position of the electrosurgical device and suspicious tissue at the most critical moments of the procedure, i.e., when the device is being advanced into tissue or activated to remove or isolate tissue.
Previous methods for dealing with the interference created by operation of an electrosurgical generator (ESG) used to power an electrosurgical device have consisted essentially of gating the operation of the ultrasonic imaging system and the operation of the ESG in a mutually exclusive sequence. That is, the ultrasonic imaging system is gated to be operated only when the ESG is not operating and vice versa. In this way, the ESG operation never interferes with the imaging process of the ultrasonic imaging system. However, this method can be difficult and expensive to adapt to an existing ultrasonic imaging system because it can require modification of the internal operation of the ultrasonic imaging system. Although new ultrasonic imaging systems could be manufactured to have such a feature built into the system, there are vast numbers of ultrasonic imaging systems currently in place and replacement of these expensive existing systems would not be practical.
In addition, mutually exclusive operation of an ESG and ultrasonic imaging system in a gated sequence may not leave sufficient time for an effective period and duty factor of operation of the electrosurgical device. Most electrosurgical instruments must be in active radiofrequency emitting mode for a minimum actual time and minimum percentage of time during use or the instrument will not effectively ablate, cut, cauterize or otherwise treat the target tissue. In addition, the ultrasonic imaging system must be actively transmitting and receiving imaging signals for a sufficient percentage of time while the operator is attempting to image a desired area in order to produce a useable image.
What has been needed is a system and method to manage, reduce or eliminate imaging system interference caused by operation of an energy emitting surgical or biopsy instrument wherein the system allows for effective contemporaneous use of the imaging system and energy emitting instrument. What has also been needed is such a system and method which can be readily adapted to existing imaging systems without the need for expensive and cumbersome modifications of the existing imaging systems.
The invention is directed generally to a system and method for managing, reducing, or eliminating the interference effects produced by the operation of interference signal generating devices in the vicinity of image signal receivers. Specifically, the invention is directed to a system for reducing the effects of electrosurgical interference on ultrasonic imaging systems when both are being operated simultaneously.
One embodiment of the invention is directed to an interference reduction system having a sync detector configured for communication with the imaging system and an interference bar detector in communication with the imaging system. A processor is in communication with the sync detector and interference bar detector. The processor is configured to calculate the position of an interference bar embedded within imaging system data from data collected by the interference bar detector. A gating and time base generator is in communication with the processor and is configured for communication with and gating of the energy emitting instrument. In a particular embodiment of the invention, the energy emitting instrument consists of an electrosurgical probe and the imaging system consists of an ultrasonic imaging system. The processor can be configured to gate the energy emitting instrument during periods of an imaging cycle corresponding to a desired portion of the image frame. The desired portion of the image frame is preferably a lateral edge of the image frame.
The interference bar detector can be a video monitor having a screen and a plurality of optical sensors in optical communication with the screen. The optical detectors are preferably photodiodes mounted in at least one linear array on the screen of the video monitor. An image enhancer may be disposed between and in electrical communication with the imaging system and video monitor in order to enhance the image data produced by the ultrasonic imaging system and enable the interference bar detector to more accurately detect an interference bar embedded in image data of the ultrasonic imaging system. In another embodiment, the interference bar detector can consist of a frame buffer in communication with the processor where the processor is configured to analyze pixels in a desired region of an image frame of imaging system data to determine whether an interference bar exists within the image frame.
In yet another embodiment of an interference reduction system, an image digitizer is configured for electrical communication with the imaging system and a processor. The processor has a frame buffer configured to store at least two image frames and which is configured to replace an interference scrambled portion of a first image frame stored in the frame buffer with a corresponding portion clear of interference from a second image frame stored in the frame buffer. A counter timer is in communication with the processor and configured to be electrically coupled to and gate the energy emitting instrument. Preferably, the energy emitting instrument consists of an electrosurgical probe and the imaging system is an ultrasonic imaging system. The processor can be configured to gate the energy emitting instrument during periods of an imaging cycle corresponding to a desired portion of the image frame which alternates position within sequential image frames so as to facilitate the replacement of interference scrambled portions within adjacent or near adjacent image frames.
In use, an embodiment of an interference reduction system manages intermittent interference imposed upon an imaging system during operation of the imaging system by gating the intermittent interference in frequency and phase to position interference scrambled portions of the imaging system data away from a desired portion of a display screen. In one embodiment, the intermittent interference is generated by an energy emitting instrument and gating of the interference is carried out by gating the operation of the energy emitting instrument. Preferably, the desired portion of the display screen is the middle of the display screen or a lateral edge or edges of the display screen.
Another embodiment of an interference reduction system manages intermittent interference of an imaging system produced by an energy emitting instrument by storing at least a first and second image frame produced by the imaging system into a frame buffer of the interference reduction system. The interference reduction system then replaces an interference scrambled portion of the first image frame with a corresponding second image frame portion that is clear of interference to produce a synthesized image frame that is substantially clear of interference. The synthesized image frame can then be displayed on a video display monitor. The first and second image frames can be temporally sequential in the frame buffer, or can be separated by one or more image frames. In addition, the first image frame can temporally precede the second image frame in the frame buffer or the second image frame may temporally precede the first image frame.
In a particular embodiment, the scrambled interference portion of the first image frame comprises an interference bar generated by an energy emitting instrument. Optionally, the energy emitting instrument can be gated in frequency and phase to position the interference bar of the image frame into a desired location within the image frame prior to replacing the interference bar of the first image frame with a corresponding second image frame portion that is clear of interference.